Question

I’m implementing some custom NSArray sort selectors and I was wondering whether there’s anything like the <=> operator in C/Objective-C?

I have this:

if (self.count == otherObject.count) return 0;
return (self.count > otherObject.count)? 1 : -1;

and would love to have (as in Perl)

return self.count <=> otherObject.count;

Answer 1

Maybe the compare: method is what you are looking for? NSString, NSNumber etc implement it. All compare-like methods in Cocoa returns a NSComparisonResult:

enum {
   NSOrderedAscending = -1,
   NSOrderedSame,
   NSOrderedDescending
};
typedef NSInteger NSComparisonResult;

So you can use the returned integer value directly. Assuming that count in your question is a NSNumber you can do:

return [self.count compare:otherObject.count];

If your case is limited to numbers and you want to use just an operator you can probably use good old minus. But be aware of integer overflow!:

return self.count - otherObject.count;